Fuel gas used in power generating plants is available, in many situations, at much higher pressure than is needed for combustion in the power generating equipment. The source of high pressure fuel gas for power generation may be a natural gas pipeline, pressurized fuel conversion gasifier, a chemical process plant, or any other high pressure combustible gas generating equipment. Usually, the fuel gas pressure needs to be reduced and controlled to the level required for stable combustion in the power generating combustion equipment, such as the combustor in a gas turbine generator, or a fuel burner in a waste heat boiler and fully fired boiler turbine generator, etc. Typically, pressure reduction is achieved by throttling the fuel gas, but this is not particularly efficient since it does not make use of the fuel gas pressure differential.